MSHTML VBufBackend: improve the code that tries to strip unneeded whitespace that...

MSHTML VBufBackend: improve the code that tries to strip unneeded whitespace that appears in IE9 documents by making sure that   whitespace is only stripped from the left if this is the first textNode in a block node.
This means it will no longer incorrectly remove the space that appears in a sentence straight after a link. The code however will always still collapse all remaining whitespace down to one single space, and also completely remove content that only has whitespace and nothing else.
The example document that showed this problem was: http://en.wikipedia.org/wiki/Big_Joe_Turner
The problem is in the intro paragraph.